Physical and theoretical models of vascular systems are being used to study a variety of hemodynamic phenomena relating to vascular diseases and proper methods of drug delivery. The following projects were emphasized during the past year: (1) We are studying the interrelationship between blood flow patterns and the mass transport of macromolecules into the arterial wall as a possible explanation of the lesion site preferences associated with atherosclerosis. We have fabricated mechanical models of a branching flow system, made of semipermeable wall material, to study convection/diffusion through the wall. We are using a computational fluid dynamics program (FIDAP) to theoretically simulate flow and transport in model arteries to corroborate our experiments. (2) We have fabricated mechanical flow models of iliac arteries to study the effects that intravascular stents may have in causing serious disturbances to the blood flow, thereby contributing to stent failure. Stents are frequently used after angioplasty to assure arterial patency, but their high incidence of restenosis is a confounding problem that may be related to flow disturbances. (3) We have studied the streaming phenomena associated with intra-arterial delivery of drug solutions via catheters into pelvic arteries for treating cervical cancer. Our results suggest that proper methods of solution injection and catheter placement can provide uniform distribution of therapeutic agent to the tumor region.